SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b020fbda7ed9932b2eb9547cf67a14548cad979015051073b6b7567efd58d8b0' 
  AND token = 'SheewaEF5mFLehvRIvoPrHPARHt0udAzo+MGPV13+qo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}